1. Field of the Invention
The invention relates to a fuel cell that has gas channel-forming members.
2. Description of the Related Art
In recent years, fuel cells that generate power through electrochemical reactions between a hydrogen gas and oxygen have been drawing attention as an energy source. A fuel battery has a structure that is formed by stacking a plurality of cells each of which is constructed by integrating a membrane-electrode assembly made up of an electrolyte membrane and electrode catalyst layers formed thereon, separators, and gas channels disposed between the membrane-electrode assembly and the separators. The gas channels feed the reactant gases that are used for electric power generation of the fuel battery, for example, a hydrogen gas, or an oxidizing gas, into the membrane-electrode assemblies.
Japanese Patent Application Publication No. 2005-310633 (JP-A-2005-310633) proposes a construction that employs an expanded metal, as a member for forming the gas channels. The expanded metal is a metal plate provided with regularly formed penetration holes of the same shape, and has been rolled into a flat platy shape.
However, in the foregoing related-art technology, although an expanded metal having many penetration holes is used, the channels are formed by streak-like recess portions that extend in a planar direction of the electrode catalyst layer, so that the directions of flow of the reactant gas are mostly in the planar direction of the electrode catalyst layer, and the reactant gas is unlikely to flow in a direction perpendicular to the plane (hereinafter, referred to as “the perpendicular-to-plane direction”). Therefore, there is a problem of the efficiency of the diffusion of the reactant gases in the gas channels cannot be sufficiently heightened.
Improvement in the gas diffusion layer is important from viewpoints of resolving the gas shortage on the electrode catalyst layer side, and is important from viewpoints of improving the drainage characteristic.